Sound absorber



Dec. 8, 1964 w. A. JACK ETAL 3,160,225

SOUND ABSORBER Filed Jan. 13, 1958 INVENTOR 5 William A.J OLCK George W LOHdSFQ'P United States Patent Office 3,160,226 Patented Dec. 8, 1964 This invention relates to acoustical treatments for room interiors, and more particularly, it relates to functional or diffraction type sound absorber for such acoustical treatments.

The use of functional or dilfraction type second absorbers for correcting the acoustical qualities of a particular room, heretofore, has been well known. These absorbers usually take the form of hollow parallelepipedons, mating hollow cones, hollow, closed-end cylinders, etc. The principle upon which these absorbers relay is that the Walls of the unit enclose a body portion of air. The material, from which the absorber is composed, is of the acoustical type and offers a suitable resistive impedance to the sound waves, and the enclosed air reduces the reactive components of the sound waves. The two combine to form a highly efficient absorber. Difliculties have been encountered in the past with these types of absorbers because they have often been fairly delicate, quite dimcult to ship because of their geometric configuration, and, because of the particular configurations, have created a large amount of waste material in their fabrication. The inevitable result has been that the cost of such units increases due to the packaging and/or shipping requirements, and due to the wastage involved. if such in" creased costs are attempted to be reduced or eliminated, as by cutting the geometric shape into a plurality of panels and shipping such panels disassembled, the manufacturing costs increase because of this added cutting, and additional problems are often created in assembling the various panels. Likewise, because of the particular configurations used, wastage has never been completely or even satisfactorily eliminated.

An object of this invention, therefore, is to provide a functional or difiraction type sound absorber which is readily adaptable to an assembly line process in that wastage of materials is completely eliminated in forms. lating or shaping the particular units.

Another object of this invention is to provide a func tional or diffraction type sound absorber which is of a simple layout, and allows the fabricating material to be packaged and shipped without difficulty in its knockeddown or disassembled form, thereby reducing the costs for such packaging and shipping.

Still another object of this invention is to provide a functional and diffraction type sound absorber which is expeditiously assembled at the installation site.

Still another object of this invention is to provide a functional or diffraction type sound absorber which is readily assembled into a particular geometric shape out of a single layer of acoustical material such as an acou tical blanket and requires no additional cementing or tacking of separated parts or panels to form an enlclosed body.

Still a further object of this invention is a novel method of fabricating a functional sound absorber from a continuous blanket of acoustical material.

A further object of this invention is a novel method of packaging and shipping functional sound absorbers in relatively compact units not readily subject to damage during shipping.

in brief, the particular invention comprises a functional type sound absorber constructed into a polyhedral geometric shape from a single layer of acoustical material such as an acoustical blanket which has marked thereon the lines of fold so that the particular shape can be constructed by merely folding the blanket along these guide lines. The particular absorber units may be packaged and shipped as a plurality of blankets, cut to the proper length and package together, and each subsequently readily assembled to form the geometric unit at the construction site by the particular journeyrnen by folding the blanket along the lines of fold.

The details of the invention, and other objects thereof, will be apparent from the following, more detailed description, and the appended drawing wherein:

FIG. 1 diagrammatically illustrates a continuous layer of acoustical blanket as received from a fabricating machine, showing the relative lcngths to which each blanket is to be cut and the lines of fold imprinted or embossed upon each blanket for forming a tetrahedron;

FlG. 2 pictorially illustrates the method of folding the blanket of FIG. 1 into the required tetrahedral shape; and

FIG. 3 is a pictorial view of the tetrahedral sound ab sorbing unit together with its means of suspension; and

FIG. 4 is a diagrammatic illustration, similar to FIG. 1, showing the relative lengths to which each blanket is to be cut and the lines of fold imprinted or embossed upon each blanket for forming a hexahedron; and

BIG. 5 pictorially illustrates the method of folding the blanket of FIG. 4 into the desired hexahedral shape.

The particular invention comprises in fabricating a light Weight, loose textured acoustical blanket, such as mineral wool, hair felt, wood fiber, etc., into a tetrahedral shape (H68. 2 and 3). The unit 1 is comprised of four sides 2, 3, d and 5, with each side taking the form of an equilateral triangle. At one of the apexes, a cap 6 is secured thereto in any conventional manner, and has a rod '7 and hook 7a extending therefrom so that the unit may be suspended from a ceiling structure. The delineated suspension means, per se, form no part of the present invention; any type of suspension means, as, for example, wires, rods, hooks, clips, etc., may be substituted for the cap 6, rod 7, and hook 7a and still remain within the spirit and intent of this invention.

In the fabrication of an acoustical blanket, such blanket is usually received from a continuous process of manufacture as one continuous layer, lla (FIG. 1) of a desired width. Following the teachings of our invention, each blanket is cut into a relatively short quadrilateral strip of a length to provide in the short strip the total area of a plurality of equilateral triangles, which later become the side panels or faces, 2, 3, 4 and 5 of tetrahedron. The particular cutters may be adjusted to cut along the parallel lines Fill and 11, at the currect angle (68) to the side edge of the blanket, as the continuous layer is received from the production line; these lines of severance fill, 11, of course, are spaced a predetermined distance apart so as to give the desired length of blanket. Thus, no waste whatsoever is created, since any particular size of unit requires only cutting the continuous blanket strip into desired lengths.

After the severed blanket is removed from the fabri cating machine, lines of demarcation l4, l5, are raced on the surface of the blanket, thereby pictorially dividing each such blanket into a plurality of equilateral triangles 2L, 3, and Lines l4, 15, 1d are construction lines, or the lines of fold which are to be followed in shaping the tetrahedron. These lines may take several forms. As illustrated in HQ. 1, they may be mere chalk lines or ink lines. in addition, if the blanket is fairly thick, lines of told M, l5, 16 may be formed by compressing, cutting away or eroding portions of the material adjacent the lines of fold. Additionally, the lines of fold may be formed by painting or spraying an organic or inorganic binder along these lines, curing or saeaaae setting the binder, and compressing it on the blanket to obtain proper adhesion and, desirably, to indent the material on the lines of intended fold so as to make folding easier on those lines. Such coating by a binder allows the thicker blankets to be folded more readily Without crinkling along the lines of folds to obtain the desired shape. The binder may be any organic or inorganic material, such as ethyl-silicate or sodiunnsilicate, or any thermo-plastic or thermosetting resin, as for example, any phenolformaldehydc resin.

After the lines of fold have been traced, embedded or embossed in the blanket, a plurality of such flat blankets are secured into a single package and shipped to the particular construction site as a unitary package. It is evident that such package can be easily and readily shipped, and the danger or" injury to the blanket is almost non-existent with common handling procedures.

Upon receipt of the packaged units, the installation crew merely takes out each blanket individually, folds each blanket following the lines of fold 1-4, 35, id, and the blanket naturally folds into the desired tetrahedral shape. The mating edges 3-9, 16-11, and 12413 may be stapled or glued together so that the particular geometric shape is fixed. The cap 6 is secured to one of the apexes and the unit is ready for suspension.

To increase the esthetic appearance of the absorber units and to prevent breathing, each such unit may be sprayed with a thin lacquer or covered with a suitable lightweight paper. This added covering does not inaterially affect the sound absorbing qualities of the units.

Following the teachings of our invention, it is evident that the invention need not be limited solely to geometric shapes of tetrahedral form. Other geometric shapes, as, for example, a hexahedron, may be fabricated which will accomplish all of the objects of our invention. Referring to FIG. 4, a continuous blanket may be divided into a plurality of panels conforming to right-angled triangles, 21-26. When such triangular panels are folded along the lines of division, or lines of told, 27-31, (FIG. the resultant geometric shape is a non-equilateral hexahedron. The suspension means, illustrated in FIG. 3, may also be utilized to suspend the hexahedron thus produced from a wall surface.

As with the tetrahedral absorber, the hexahedron accomplishes all of the objects of our invention. Thus, the continuous blanket (FIG. 4) has no Waste as each absorber may be severed along lines 32, 33 producing a quadrilateral strip of the required length; the blanket strip may be packaged and shipped in a manner similar to the simple packaging and shipping arrangement followed With the tetrahedral absorber; the lines of fold 27-31 may be inscribed, indented, etc., as with the tetrahedral shape described; and the hexahedral unit may be assembled at the installation site similar to the assembly procedure used with the tetrahedral unit.

Consequently, it is possible that other geometric shapes of sound absorbers may be fabricated utilizing the teachings of our invention. These other shapes, pro- 4- vided they accomplish the objects and follow the principles of our invention, are believed to come Within the spirit and intent of our invention.

Having thus described our invention in rather full detail, it will be understood that these details need not be strictly adhered to but that various changes and modifications may suggest themselves to one skilled in the art, all falling within the scope of the invention as defined by the subjoined claims.

What we claim is:

l. A. blank for being readily bent and assembled into a space sound absorber of polyhedral shape, comprising a sheet of relatively lightweight fibrous material, the sheet being divided by indented fold lines into a plurality of geometrical shapes, each fold line forming a common edge or" adjacent geometrical shapes, and binder material coating the sheet at the fold lines.

2. A blank as recited in claim 1, wherein the sheet is of parallelogram shape having diagonally opposed corner angles of degrees and degrees, the sheet having fold lines along the bisectors of the 120 degree angles and an additional fold line joining the inner ends of the first fold lines and being substantially parallel to the ends of the sheet.

3. A method of forming a blank which may be readily bent and assembled into polyhedral space sound absorbers, comprising the steps of indenting a sheet of relatively lightweight fibrous material along lines dividing the sheet into a plurality of geometrical shapes, each indented line forming a common edge of adjacent geometrical shapes, and coating the indented lines with binder material to permit the sheet to be easily folded along the indented lines.

4-. A method of forming a blank as recited in claim 3, wherein the sheet is of parallelogram shape having diagonally opposed corner angles of 60 degrees and 120 degrees, two indented lines extending along the bisectors of the 120 degree angles and a third indented line joining the inner ends of the first two lines and being substantially parallel to the ends of the sheet.

204,441 Marshall June 4, 1878 1,782,399 Amy Nov. 25, 1930 1,916,908 Stacey et al July 4, 1933 2,113,128 Cunnington Apr. 5, 1938 2,354,186 Donahue July 25, 1944 2,390,262 Mazer Dec. 4, 1945 2,426,899 Pantalone Sept. 2, 1947 2,502,016 Olson Mar. 28, 1950 2,694,351 Winkler et a1. Nov. 16, 1954- 2,783,690 Crary et al. Mar. 5, 1957 2,882,990 Mustoe Apr. 21, 1959 2,897,908 Barshefsky Aug. 4, 1959 FOREIGN PATENTS 746,949 Great Britain Mar. 21, 1956 

1. A BLANK FOR BEING READILY BENT AND ASSEMBLED INTO A SPACE SOUND ABSORBER OF POLYHEDRAL SHAPE, COMPRISING A SHEET OF RELATIVELY LIGHTWEIGHT FIBROUS MATERIAL, THE SHEET BEING DIVIDED BY INDENTED FOLD LINES INTO A PLURALITY OF GEOMETRICAL SHAPES, EACH FOLD LINE FORMING A COMMON EDGE OF ADJACENT GEOMETRICAL SHAPES, AND BINDER MATERIAL COATING THE SHEET AT THE FOLD LINES. 